1. Field of the Invention
The present invention relates to a liquid discharge head which discharges liquids such as ink or the like, and a method of manufacturing the relevant liquid discharge head.
2. Description of the Related Art
As an energy generating element (liquid discharge element) which generates energy for discharging liquids from a liquid discharge port provided on a liquid discharge head, the element which uses an electromechanical transducer such as a piezoelectric element or the like and the element which uses an electrothermal transducer for heating liquids through a heat generating resistor are used.
Besides, discharge energy generating elements, circuits for driving the discharge energy generating elements, a temperature sensor and the like are formed on a liquid discharge substrate. Further, to drive the liquid discharge elements at appropriate timing and to read information from the temperature sensor, the liquid discharge substrate exchanges digital signals, driving power, analog signals and the like with the outside of the liquid discharge head. Therefore, an electrical wiring substrate which is composed of a flexible circuit substrate and the like is used as measures for establishing such electrical connections.
More specifically, an external connection terminal of a recording element substrate and a terminal of the electrical wiring substrate are first set to be close to each other, and then wire bonding, inner lead bonding (ILB), an anisotropic conductive film (ACF) or the like is used to establish the electrical connection between these terminals.
The electrical connection portion between the liquid discharge substrate and the electrical wiring substrate is coated with a sealing resin so as to be protected from corrosion of the electrical connection portion due to liquid and disconnection of the wirings due to external force (see Japanese Patent Application Laid-Open No. 2002-019120). Typically, as shown in FIG. 44, the sealing portion of the electrical connection portion is formed by linearly applying a thixotropic sealant 511a along the line of electrical connection portions 510 with use of a needle 520 of the dispenser for applying the sealant (see Japanese Patent Application Laid-Open No. H10-000776). As shown in FIG. 44, the height of the sealing portion of the electrical connection portion 510 can be determined based on the position of the end of the needle 520 set at the time of applying the sealant. Thus, to prevent a risk that the end of the needle comes into contact with the electrical connection portion and thus damages it, in consideration of tolerance of parts, errors of device operations, and the like, the sealant 511a is applied in the state that a certain level of clearance between the end of the needle and the electrical connection portion is maintained.
In recent years, the liquid discharge head is requested to discharge liquid droplets with a high degree of accuracy of impact. Furthermore, according as the size of a liquid droplet becomes small, a possibility of being influenced by disturbances such as air stream and the like becomes high if a discharge distance of the ink droplet is long. As a result of consideration, it has been found that, to suppress errors of impact positions, it is most effective to further shorten the distance between the opening surface of the liquid discharge port and the medium to which the ink droplet is impacted. At this time, since the portion in the liquid discharge head closest to the medium is the top of the sealant of sealing the electrical connection portion, it is necessary in a liquid discharge device which is equipped with the liquid discharge head to suppress and thus lower the relative height between the opening surface of the liquid discharge port and the top of the sealant so that the sealant and the medium satisfy the position relation that the sealant is not in contact with the medium. However, in this case, if the height of the sealant is suppressed by a conventional method, there occurs a problem that the electrical connection portion is damaged and/or exposed.